Semiconductor production devices performing process steps for producing semiconductors are disposed inside a isolated space that is isolated from the outside and remarkably reduced in dust for the purpose of preventing adhesion of dust to a semiconductor substrate. In order to prevent the dust adhesion to semiconductor substrate, the semiconductor substrate is conveyed between the semiconductor production devices by an OHT conveyer vehicle in a state where the semiconductor substrate is housed in a carrier such as a FOUP that has a housing space for housing the semiconductor substrate in its internal part. A load port capable of providing communication between the isolated space and the outside is provided on a wall defining the isolated space, and the semiconductor substrate is delivered between the FOUP and the semiconductor production devices by the load port when the housing space and the isolated space are connected to each other.
In a semiconductor production device, i.e. semiconductor production unit, disclosed in JP-A-2003-318244, two load ports are disposed adjacent to each other on a wall defining a chamber, i.e. isolated space. When a FOUP is connected to the load port, a conveyer robot delivers a semiconductor substrate between the FOUP and an alignment unit, i.e. semiconductor production device, disposed inside the chamber. With the provision of the two load ports for one isolated space, the FOUP is placed on one of the load ports during processing on the FOUP placed on the other load port by the semiconductor device, and processing on the semiconductor substrate of the FOUP placed on one of the load ports is performed immediately after completion of the processing on the semiconductor substrate of the FOUP placed on the other load port, thereby improving a use efficiency of the semiconductor production devices.